1. Field of the Invention
The present invention concerns novel polyfluoride sulfonium compounds, a process for producing thereof, a cationically polymerizable composition containing the polyfluoride sulfonium compounds, a polymerization initiator comprising the polyfluoride sulfonium compounds as the main ingredient and a polymerization process using the polymerization initiator. More specifically, the present invention relates to a cationically polymerizable composition containing a novel polyfluoride sulfonium compound useful for obtaining a curing product having satisfactory property or an oligomer of a cationically polymerizable vinyl compound having practical usefulness by polymerizing the cationically polymerizable material in a short period of time by means of heat or radiation rays such as light or electron rays, a polymerization initiator for such polymerization and a polymerization process.
2. Discussion of Background and Material Information
Generally, cationically polymerizable materials, which have used epoxy resins have been employed for various applications requiring materials of high performance. This is particularly so where the method of curing by polymerization under the irradiation of radiation rays at predetermined wave length, such as ultraviolet rays, can provide curing within a short period of time by a simple polymerization step.
Epoxy resins have so far been used generally in the form of a two-component system by incorporating an active amine-containing compound or a carboxylic acid anhydride as a curing agent. However, the two-component system using such a curing agent involves a drawback that the ingredients have to be mixed completely and it needs curing times as long as several hours.
In addition, there is also known a boron trifluoridemonoethyl amine system for curing the epoxy resin in a one component system but it takes from 1 to 8 hours even at high temperatures of 160.degree. C. or higher. As an improvement there can be mentioned U.S. Pat. No. 3,565,861 even though this patent also requires high temperature. Accordingly, these compositions can not be used for the coating of heat sensitive electronic parts, and other applications which cannot tolerate high temperatures. Further, in the case of curing an epoxy resin by light, there has been proposed a method of using a aryl diazonium metal polyhalide complex. However, polymerization takes place rapidly and premature gelation tends to occur in this method. In addition, such compositions cannot be stored satisfactorily even for a short period of time in a dark place. In view of the above, it has been proposed to suppress the premature gelation of the composition and provide storage-stability in a dark place for epoxy material containing a aryl diazonium metal polyhalide complex. However, since nitrogen is released during curing from such a composition, the resultant curing material involves a problem of incorporating bubbles in the product, which increases costs and causes completely unsatisfactory results.
Various photodegrading sulfonium salts have been known for the onium salt. For instance, it has been known to use p-hydroxyphenyldimethylsulfonium hexafluorarsenates as a photocuring agent in Japanese Patent Publication No. Sho 54-53181 and phenylsulfonium salt as a photocuring agent for epoxy resins in Japanese Patent Publication No. Sho 50-151997. However, although such onium salts can photocure epoxy resins, epoxy resins can not be cured by merely applying heat.
On the other hand, as the thermal latent type catalysts capable of activating onium salts by applying heat thereby curing epoxy resins, there have been reported benzylsulfonium salt, for example, dialkylbenzylsulfonium hexafluoroantimonate in Japanese Patent Publication Nos. Sho 58-37003 and Sho 63-223002 and a trialkylsulfonium salt in Japanese Patent Publication No. Sho 56-152833. However, these sulfonium salts are inert to light and cannot cure epoxy resins in a short period of time. They also require temperatures, for example, of 150.degree. C. or higher, and can not be said to be practical in view of the heating time and temperature.
Further, Japanese Patent Publication No. 60-188425 discloses a curing agent for the heat polymerization of special esters such as spiro type esters.
On the other hand, as the cationic polymerization initiator for cationically polymerizable vinyl compounds, there have been known Lewis acid catalysts such as mineral acid, BF.sub.3, ZnCl.sub.2, AlCl.sub.3 and halogen-containing organic aluminum compounds such as AlR.sub.2 Cl and AlRCl.sub.2. These catalysts, however, cause a violent cationic polymerization reaction at a temperature of 0.degree. C. or higher which reaction can not be controlled as desired, and the polymerization degree can not be increased. It is of course impossible to previously formulate a cationically polymerizable monomer and such a catalyst into a one component system at room temperature which can be stored.
For polymerizing a vinyl compound, it has been generally necessary to control the chain transfer reaction or to stop the reaction. Accordingly, the polymerization reaction has usually been conducted by charging a catalyst solution into the system after cooling a cationically polymerizable monomer dissolved in an appropriate solvent to predetermined extremely low temperatures. However, for conducting the polymerization reaction on an commercial basis an extremely low temperature (for instance from -130.degree. C. to -40.degree. C.) is employed. This makes the operation complicated and increases the cooling cost and, accordingly, it is not satisfactory. Although U.S. Pat. No. 3,283,010 describes the release of benzyl cations, polymerization of the polymer is not intended.
Besides the foregoing citations, p-hydroxyphenyl benzylsulfonium compound is disclosed in Japanese Patent Publication Sho 50-29511 and p-hydroxyphenylbenzylsulfonium halide is disclosed in U.S. Pat. No. 4,034,046. However, (sub)metalpolyfluorides of a substituted or non-substituted oxyphenylbenzylalkylsulfonium compound has not yet been known.